Aging is a major risk factor for many chronic diseases such as cardiovascular disease, neurodegenerative disease, and cancer. As the global population progressively ages, age-related diseases have become some of the world?s most prominent health problems. The established medical practice has thus far focused on treating each disease independently as it arises. With this conventional approach, age-related diseases are quickly becoming unmanageable collectively, as alleviating one disease for an individual does not prevent the inevitable rise of another one. A fundamental shift of paradigm in treatment and prevention would be to target the root cause of aging, instead of its ?symptoms?. Under this new paradigm, rejuvenation of aging human tissues and organs represents a promising and fundamentally new direction. Here we propose an unconventional approach to tackle one of the grandest challenges of our time ? to systematically identify strategies for rejuvenation. Our proposal is based on a novel concept: rejuvenating aging human cells through transcriptional reprogramming. This was inspired by Yamanaka?s success in deriving induced pluripotent stem cells from differentiated cells through transcriptional reprogramming. The fundamental hypothesis is that both ?young? and ?old? are different states of the cell defined by specific gene expression programs, and that by introducing appropriate combinations of transcription factors (TFs) into the old cells, it is possible to directly rejuvenate the old cells and bring them back to the youthful state. To test this hypothesis and to identify such transcriptional programs, we will develop a novel approach that combines the CRISPR technology for targeted gene regulation, single cell RNA sequencing for gene expression profiling, and state-of-the-art bioinformatic analysis. Using established human cell culture models for aging study, we will systematically identify combinations of TFs that, when introduced to old cells, are able to reverse the gene expression program of the old cells to that of the young cells. Positive hits from the high throughput screening will be followed by detailed cellular and molecular phenotyping to confirm the effect of rejuvenation. The identification of combinations of TFs capable of rejuvenation will set a unique stage for discovering combinations of small molecule drugs that can achieve the same effect. Drugs that activate each individual TF can be screened using transcriptional reporters, and positive hits for different TFs can be combined. This reduce the impossible problem of searching for combination drugs for cell rejuvenation to a much more manageable problem of searching for a single drug that activates a specific TF.